The present invention relates to a work loading method for an automatic palletizer preferable for reduction in cycle time of press working, a work loading method and a work loading apparatus that are preferable for positioning a work, which is carried out of a press, with a centering device and transferring it to a pallet with a robot and the like, and an attachment replacing method for the work loading apparatus, which is preferable for replacing an attachment for positioning the work and an attachment of a loading robot for holding the work, according to the work.
An automatic palletizer which is placed at a work carrying-out side of a press line is for automatically holding and transferring a worked work (a panel and the like), which is carried out with a carrying-out conveyor or the like and is positioned with a centering device, and loading it into a pallet to house it therein. Here, as one of important factors to improve cycle time of a press work line, the cycle time of an automatic palletizer is cited. Several automatic palletizer systems are conventionally proposed for this purpose, and for example, the automatic palletizer apparatus disclosed in Japanese Granted Patent No. 3134599 is known. FIG. 36 and FIG. 37 are a plan view and a side view of the automatic palletizer apparatus disclosed in the same patent, and the prior art will be explained below according to FIG. 36 and FIG. 37.
A carrying-out conveyor 154 is provided at a work carrying-out side of a press 152, and a vertically separating conveyor 155 for vertically separating works W is provided at an end portion of the carrying-out conveyor 154 at a downstream side. Conveyors 156 and 157 are respectively provided at an upper and lower carrying-out ports of the vertically separating conveyor 155, and two out of palletizing robots 161a, 161b, 161c and 161d are placed on a left and two on a right in a work transfer direction of each of the conveyors 156 and 157, four palletizing robots in total. Each of the robots 161a to 161d holds and transfers the worked works W, which are positioned by centering devices (not shown) provided at the conveyors 156 and 157, and loads them into a pallet 162 to house them therein.
In the automatic palletizer apparatus disclosed in the above-described Japanese Granted Patent No. 3134599, palletization is performed with a plurality of robots 161a to 161d, and therefore the cycle time can be improved. However, in order to avoid interference between a plurality of robots, they are placed with the large spacing between them in the vertical and horizontal directions. Consequently, a large installation space is required for the automatic palletizer apparatus, thus causing the problem that the entire press line becomes long and the exclusive area of the line occupies a large area in the factory building area. For such a reason, an automatic palletizer apparatus, which can respond to a short cycle time of press working by reducing the installation space for a plurality of robots and eliminating the interference between the robots, is demanded.
Incidentally, when a work such as a panel carried out of the transfer press is loaded into the pallet with use of the robots, cycle time of the devices at the downstream side such as loading robots takes a longer time with respect to the cycle time of the press (press cycle), which becomes an obstacle in the improvement in the cycle time of the entire press working line. As loading devices to solve this problem, the ones that are disclosed in Japanese Granted Patent No. 2677082 and the above-described Japanese Granted Patent No. 3134599 are known.
FIG. 38 is a plan view of a work loading device disclosed in Japanese Granted Patent No. 2677082. A feed bar 70 for carrying out the work W such as a panel that is worked by forming by the transfer press located at the left side of FIG. 38 is provided at the carrying-out side of the press. A transfer conveyor 72, which receives the work W from the feed bar 70 and transfers it to a positioning device 73 in the direction shown by the arrow T in FIG. 38 by intermittent feeding, is provided to penetrate through the positioning device 73. Pallet transfer devices 76 and 77, which carry the pallets 71 in and out of two loading stations 74 and 75 at the upper and lower side of FIG. 38, are placed. Two robots 78 and 79, which alternately hold the work W positioned by the positioning device 73 and load it into pallets 71 located at the aforementioned respective loading stations 74 and 75, are placed between the positioning device 73 and each of the pallet transfer devices 76 and 77, respectively.
According to the above-described constitution, a loading operation is alternately performed by two of the robots 78 and 79 for one of the positioning device 73, and therefore each of the robots 78 and 79 loads the work W for every two shots of the transfer press. Consequently, each of the robots 78 and 79 can move to the next operation while avoiding interference between the robots during the cycle time of each other in order that the cycle time is within two press cycles, whereby the cycle time of the work loading is reduced to make it possible to improve productivity.
However, in the work loading device disclosed in Japanese Granted Patent No. 2677082, two of the robots 78 and 79 perform a loading operation at the same time when the work of transfer press is two-piece working. Consequently, the cycle time of the robots does not catch up with the press cycle, and the cycle time of the entire press working line has to be increased, thus reducing productivity. The two-piece working is to work the works by dividing the works laterally into two in the transfer direction for each one shot of the press.
The aforementioned FIGS. 36 and 37 are also the work loading devices. Namely, the carrying-out conveyors 154 and 154, which are placed side by side laterally in two rows and transfer the works W worked by forming by the press 152 to an inspection station 153, are provided at the press 152. A pair of vertically separating conveyors 155 and 155 on the left and right, which are able to oscillate in an up-and-down direction around an oscillation center O by the operation of a cylinder unit 155a, are provided to be able to receive the works W from the carrying-out conveyors 154 and 154 at the downstream side of the carrying-out conveyors 154 and 154, connectingly to the inspection station 153. A pair of left and right carrier conveyors 156 and 156 at an upper part and a pair of left and right carrier conveyors 157 and 157 at a lower part are provided at the downstream side of the vertically separating conveyors 155 and 155 to be able to receive the works W that are vertically separated at the vertically separating conveyors 155 and 155. The carrier conveyor 157 at the lower side is provided to extend to the downstream side to be longer than the carrier conveyor 156 at the upper side. Further, the respective end portions at the downstream side of the carrier conveyors 156 and 157 form work positioning sections 158, and a positioning lifter 160 for positioning is provided at a lower part of each of the work positioning sections 158. The robots 161a, 161b, 161c and 161d which take out the works W transferred to the respective work positioning sections 158 by the carrier conveyors 156 and 157 and positioned are placed at the side of the respective work positioning sections 158. The pallets 162 and 162 into which the works W are loaded are placed at both sides of each of the robots 161a to 161d. 
According to the above-described constitution, the works W that are carried out of the press 152 are alternately separated vertically by the vertically separating conveyors 155 and are transferred to the work positioning sections placed up and down. Consequently, each of the robots 161a to 161d loads the work W every two shots of the press 152. Therefore, by containing the cycle time of each of the robots 161a to 161d within the two press cycles, the cycle time of the entire press work line is reduced to improve productivity.
However, in the above work loading device, the vertically separating conveyors 155 are needed, which complicate the apparatus and increase the cost. The cycle time for carrying the works into the pallets 162 is restricted by an operation time of the vertically separating conveyors 155, thus making it impossible to take advantage of the short cycle time of the robots themselves, and making it difficult to further improve the cycle time of the entire press work line.
Conventionally, when the work such as a panel after worked in a press work line such as a transfer press is loaded into a pallet, the work transferred with a transfer conveyor is positioned by a predetermined guide member (a so-called nest) of a centering device. A work loading apparatus, which holds and transfers the positioned work with the transfer robot and loads the work into the pallet located at a predetermined position so that the work does not fall therefrom, is frequently used. On this occasion, when changing the kind of the works, it is necessary to replace the attachment such as a guide member of the centering device, and the attachment for holding the work such as a suction device of a transfer robot at the same time corresponding to the shape and the size of the work. Consequently, a work loading apparatus provided with a replacement device for these attachments is known.
As the work loading apparatus provided with such a replacement device for the attachments, there is for example, the one disclosed in the above-described Japanese Granted Patent No. 2677082. The aforementioned FIG. 38, and FIG. 39 and FIG. 40 are the work loading apparatus, a side view and a front view of a replacement device for the attachments, which are disclosed in the same patent. Concerning FIG. 38, the positioning device 73, the pallet 71, the robots 78 and 79 are as described in the above.
Further, in FIG. 38, two of attachment delivery devices 81 and 82 of the same specification are placed along the transfer conveyor 72 between the transfer conveyor 72, and two of the pallet transfer devices 76 and 77, respectively. Out of them, the attachment delivery device 81 on the upper side of FIG. 38 is in charge of delivery of each attachment for the positioning device 73 located at the side of the robot 78 and an attachment for the robot 78. The attachment delivery device 82 on the lower side is in charge of delivery of each attachment for the positioning device 73 located at the side of the robot 79 and an attachment for the robot 79. Two of the attachment delivery devices 81 and 82 are provided with a supply moving stand 85 as a first moving stand which holds an attachment supply part 84 at a low position and a receiving moving stand 87 as a second moving stand which holds an attachment receiving part 86 at a high position to be movable back and forth along a common guide rail (not shown), on a base stand 83 extending from an area near a base part of each of the robots 78 and 79 to a tip of a terminal end portion of the transfer conveyor 72 in parallel with the transfer conveyor 72. The attachment supply part 84 and the attachment receiving part 86 can hold a lifter attachment 88 and a side guide attachment 89 for the positioning device 73, and a robot attachment 90.
According to the above-constitution, an operation of loading the work W into the pallet 71 is alternately performed by two of the robots 78 and 79. When the attachment replacement for the next work is performed, the next attachment to be used is placed on the attachment supply part 84 in the state in which the supply moving stand 85 and the receiving moving stand 87 are in a retreat position. At the time of replacement, the supply moving stand 85 and the receiving moving stand 87 are moved forward together, and the attachment receiving part 86 and the attachment supply part 84 are placed by laying one over the other at a position within the operation range of the robots. Next, the used attachments 88 and 89 of the positioning device 73 and the attachments 90 of the robots themselves are placed on the attachment receiving part 86 with two of the robots 78 and 79. Subsequently, only the receiving moving stand 87 is retreated, and the attachment receiving parts 86 are located outside the operation range of the robots 78 and 79. Thereafter, the next attachments to be used, which are placed on the attachment supply parts 84 of the supply moving stands 85, are taken up to mount them to the positioning device 73, and the next attachments to be used which are placed on the attachment supply parts 84 are attached to the robots themselves with the robots 78 and 79. Thereafter, the supply moving stand 85 is retreated to locate the attachment supply part 84 outside the operation range of the robots 78 and 79, and then off-line setup is carried out. As described above, since the attachment receiving part 86 and the attachment supply part 84 are placed by laying one over the other at a position within the operation range of the robots, a planar space used for receiving and supplying the attachments within the operation range of the robots can be made extremely small.
However, the attachment replacement device of the work loading apparatus disclosed in the above-described Japanese Granted Patent No. 2677082 is an exclusive device for replacing the attachments, and though the installation space for the device is reduced as compared with the prior art, a predetermined installation space is still necessary. However, the installation space is desired to be as small as possible so that the limited building area of a factory can be effectively used, and further reduction in the space for the entire work loading apparatus is needed. In addition, there are three kinds of attachments, that are, the lifter attachment 88 and the side guide attachment 89 for the positioning device 73, and the robot attachment 90, and these attachments are individually removed and mounted with the robots. Consequently, it takes a long time to mount them, thus causing the problem of reducing operability at the time of setup.
The present invention is made in view of the above-described problems, and has its object to provide a work loading method of an automatic palletizer which is capable of reducing an installation space for a plurality of robots, and correspond to a short cycle time of press work by eliminating interference between the robots. The present invention has another object to provide a work loading method and work loading apparatus which are capable of reducing a press cycle time with excellent in productivity. The present invention has still another object to provide a work loading apparatus and its attachment replacing method, which require a small installation space and is capable of reducing an attachment replacing time.
In order to attain the above-described object, a first aspect of the work loading method of the automatic palletizer according to the present invention is a work loading method of an automatic palletizer for loading a work, which is carried out of a press, into a pallet by a robot, including the steps of: positioning the works with two centering devices at an upstream side and a downstream side in a work transfer direction every other press shot; and making pairs of two robots each, which are located diagonally from each other, out of four of said robots in total, two of which are on a left and two of which are on a right to oppose each other in the work transfer direction with two of said centering devices between them, the two robots of each pair holding the works, which are on two of said centering devices, and performing a loading operation of the works into the pallets, each pair alternately holding the works and performing the loading operation each time two of the centering devices position the works.
According to the above method, the four robots are located at four corners of substantially a rectangle, and therefore the installation space for the robots can be reduced. Since each pair at the diagonal positions is alternately operated, the robots can be operated without interfering with each other even at a place where interference easily occurs above the centering device or above the pallet even if the distance between the robots is small. Accordingly, the four robots can operate with each standby time being reduced, and therefore the cycle time can be dramatically reduced.
Further, in the work loading method of the automatic palletizer: while the pair of robots are under a holding operation of the works, the other pair of robots may perform a loading operation of the works into the pallets, or may be on standby for entry into the work holding operation position; and while the pair of robots are under the loading operation of the works into the pallets, the other pair of robots may perform the holding operation, or may be on standby for entry into the aforesaid work loading positions
It is at the time of the work holding operation above the centering device and at the time of work loading operation above the pallet that the interference between a plurality of robots easily occurs on loading the works. Consequently, in the present method, two pairs are made by pairing two robots, which are located diagonally from each other, and each pair alternatively performs the work holding operation and work loading operation, and therefore the interference between the robots can be prevented with reliability.
Further, the work loading method of the automatic palletizer may further include the step of: on performing work loading into the pallet, outputting an interference area entry interlock signal of the each robot to an upper controller, and confirming interlock of prevention of interference between the robots via the upper controller.
According to the above method, since the interference area interlock signal of each robot is outputted to the upper controller and each interlock signal is monitored via the upper controller, the operation program of the robot is simplified, and can be constituted by a short program. Consequently, creation of the operation program and maintenance are extremely facilitated, and processing arithmetic operation speed is enhanced, and therefore arithmetic operation processing of the servo control processing of the robots can be performed at high speed.
A second aspect of the work loading method of the automatic palletizer according to the present invention is a work loading method of an automatic palletizer for loading a work, which is carried out of a press, into a pallet by a robot, and includes the step of: controlling a loading position of the work based on a number of the works already loaded into the pallet before start of a work loading operation, and a number of works to be loaded into the pallet by the work loading operation.
According to the above method, even when the works are already loaded into the pallet before the start of the work loading operation, the total number of the loaded works are computed based on the number of the works already loaded in the pallet and the number of the works loaded into the pallet by the work loading operation. Based on the arithmetically operated total number of loaded works, the loading position (release position) of the work to be loaded next is obtained, and the robot is controlled to be at the position. Consequently, the works can be also loaded into the short-loaded pallet, and the total number of loaded works can be accurately controlled. As a result, management of the pallet becomes easy, and excellent operability is provided. A teaching operation does not have to be performed at each work loading position in the pallet, and the number of teaching points can be reduced to be smaller than the maximum number of loaded works in each pallet, thus facilitating the teaching operation.
The work loading method according to the present invention includes the steps of: positioning works, which are carried out of a press, with a plurality of centering devices located directly under a downstream of the press or a carrying-out conveyor attached to the press; and taking up the works, which are positioned by the plurality of centering devices every plurality of press cycles, to load them into pallets by a plurality of pairs of loading robots.
A first aspect of the work loading apparatus according to the present invention is a work loading apparatus for loading a work, which is carried out of a press, into a pallet and includes: a plurality of centering devices which are located directly under a downstream of the press or a carrying-out conveyor attached to the press; and a plurality of pairs of loading robots for taking up the works positioned by the centering devices to load them into the pallets.
According to the work loading method and the first aspect of the work loading apparatus, the works positioned by a plurality of centering devices every plurality of press cycles are loaded by a plurality of pairs of loading robots, alternately by each pair. Consequently, even when the cycle time of the robots is longer with respect to the press cycle, (for example, about twice), the loading operation of the works of a plurality of cycles, which are worked every plurality of press cycles, can be processed. Consequently, the press working line with a short cycle time (good productivity) making the most of the working speed of the press can be constructed.
When the press performs single-piece working (namely, one work is worked per one shot of the press 1), the loading robots made pairs each corresponding to the centering devices take up the works every press cycles, alternately by each pair. When the press performs two-piece working, the loading robots made pairs each corresponding to the centering devices take up the works at the same time every plurality of cycles. As a result of these, the press work line with high general versatility, which can correspond to the case of single-piece working and in the case of two-piece working, can be constructed. Further, since the centering devices are placed directly under the downstream of the press or the carrying-out conveyor, the press cycle time can be shortened without being influenced by the cycle time of the separating device at the midpoint used in the prior art and the like, and the press work line can be built in the compact space.
Further in the work loading apparatus, it is preferable that the loading robots are movable in substantially a horizontal direction along substantially a work transfer direction. According to the constitution, the robots having the possibility of interference can move in the direction to be away from each other, and interference prevention can be easily achieved. As a result that the robots move close to the centering devices and take up the works, the operation stroke of the robots can be made shorter and the cycle time can be reduced. The robots can load the works into the pallets from the desired positions, thus facilitating interference prevention between the work guides provided at the pallets and the robot arms, thus making it possible to provide the work guides of the pallets at the optimal positions.
Further, in the work loading apparatus, it is preferable that the pallets are placed on both sides of the centering devices. According to the constitution, when different kinds of works are produced on the left and the right with two-piece working, different works respectively correspond to and are loaded into the pallets at both sides, and therefore even if the number of the works housed in the pallet differs for each kind of work, each pallet is filled with the works, thus making it possible to enhance the pallet housing efficiency.
A second aspect of the work loading apparatus according to the present invention is a work loading apparatus for positioning a work, which is carried out of a press, with a centering device, and loading the positioned work into a pallet with a robot, including: a pallet feeder which makes the pallets movable between a work loading position within a movable range of the robot and a predetermined position outside the movable range; and any pallet out of the pallets loaded on the pallet feeder houses at least either one of a used attachment for the centering device or a used attachment for the robot; and the pallet, which is the same as or a different from the pallet housing at least either one of the used attachment for the centering device or the used attachment for the robot, houses at least either one of the attachment for the centering device to be used next or the attachment for the robot to be used next.
Further, the attachment replacing method of the work loading apparatus according to the present invention is an attachment replacing method of a work loading apparatus for positioning a work, which is carried out of a press, with a centering device and loading the positioned work into a pallet with a robot, the attachment replacing method being of replacing at least either one of an attachment for the centering device or an attachment for the robot according to the work, includes: a first step of housing at least either one of a used attachment for the centering device or a used attachment for the robot into at lease any one of the pallets loaded on a pallet feeder which makes the pallets movable between a work loading position within a movable range of the robot and a predetermined position outside the movable range; and a second step of attaching at least either one of the attachment for the centering device to be used next or the attachment for the robot to be used next, which is placed on the same pallet as or a different pallet from the pallet housing at least either one of the used attachment for the centering device or the used attachment for the robot, to the centering device itself, or the robot.
According to the second work loading apparatus and its attachment replacing method, the used attachment for the centering device and/or the used attachment for the robot, and the attachment for the centering device and/or the attachment for the robot to be used next are placed on the pallets for the attachment. Then the pallets are transferred with xe2x80x9cthe pallet feeder for transferring the work loading palletsxe2x80x9d conventionally used in the work loading apparatus. Consequently, the exclusive attachment replacing device as in the prior art is not necessary. As a result, the installation space for the exclusive attachment replacing device is not needed, thus making it possible to reduce the installation space for the entire work loading apparatus and reduce the production cost.
Further, in the work loading apparatus: the centering device may include a centering bracket; and a plurality of attachments for the centering device may be attached to the same centering bracket. According to the constitution, a plurality of attachments having the positioning function of the centering device are attached to the same centering bracket. Consequently, the attachments for the same centering device are integrated, and can be attached and detached at one operation, thus providing excellent operability at the time of replacement of the attachments and making it possible to reduce the time required for setup.